There has been typically used a buckle that detachably engages a plug with a socket in order to connect a string member such as a belt in various applications such as clothes, bags, shoes and packages.
Such a buckle is required to be easily handled for connecting and releasing and not to cause an accidental release when the buckle is not intended to be released. For this reason, a considerable care is given for an engagement structure of the buckle.
As such a buckle, a side release buckle that is released in a manner to hold both sides of the socket has been known. One of such side release buckles is structured for engagement in a thickness direction of the buckle.
For instance, a side release buckle disclosed in Patent Literature 1 and 2 includes a plug and a socket into which the plug is inserted for engagement.
The plug includes a base and a pair of legs that respectively project from the base and are elastically deformable in a direction intersecting an insertion direction of the plug. At a tip end of each of the legs (an end thereof in the insertion direction of the plug), an engaging portion projecting in the thickness direction of the plug (a direction orthogonal to the insertion direction of the plug and a deformation direction of the legs) is formed.
On the other hands, the socket includes a body having an insertion hole and an engaged portion that is formed to be a hole or a concave portion in the body and is engageable with the engaging portion in the thickness direction.
Such a side release buckle is released by a buckle-widthwise operation of holding both sides of the socket, However, the engaging portion of the plug and the engaged portion of the socket are brought into engagement in the thickness direction of the plug, whereby the engagement is reliably maintained.